On Fri, 2016-09-16 at 11:16 -0700, Andy Lutomirski wrote: > Hi all- > > Here's v4 of the APST patch set. The biggest bikesheddable thing (I > think) is the scaling factor. I currently have it hardcoded so that > we wait 50x the total latency before entering a power saving state. > On my Samsung 950, this means we enter state 3 (70mW, 0.5ms entry > latency, 5ms exit latency) after 275ms and state 4 (5mW, 2ms entry > latency, 22ms exit latency) after 1200ms. I have the default max > latency set to 25ms. > > FWIW, in practice, the latency this introduces seems to be well > under 22ms, but my benchmark is a bit silly and I might have > measured it wrong. I certainly haven't observed a slowdown just > using my laptop. > > This time around, I changed the names of parameters after Jay > Frayensee got confused by the first try. Now they are: > > - ps_max_latency_us in sysfs: actually controls it. > - nvme_core.default_ps_max_latency_us: sets the default. > > Yeah, they're mouthfuls, but they should be clearer now. >
I took the patches and applied them to one of my NVMe fabric hosts on my NVMe-over-Fabrics setup. Basically, it doesn't test much other than Andy's explanation that "ps_max_latency_us" does not appear in any of /sys/block/nvmeXnY sysfs nodes (I have 7) so seems good to me on this front. Tested-by: Jay Freyensee <james_p_freyen...@linux.intel.com> [jpf: defaults benign to NVMe-over-Fabrics]
